13Sliding Old structures may not be strongly bolted into the foundation Corrosion weakens attachmentsThese structures could be bolted to the foundation.Weak foundations are quite derogatory to the building’s strength. They could either be poorly built, or weathered down over time. In an earthquake, a weak foundation would cause huge devastation, as the very bottom of the house would fail, resulting in a likely collapse. Some of these elements are far from attainable in modern architecture, as square skyscrapers are hardly the style. This is where earthquake engineering comes into play. Developments in this field can help buildings stay safe even if they didn’t meet all of the above ideal requirements.
42OverpassesPillars:Spiral steel girders support columns and prevent bending of steel rods in the highway The reinforcement of base, freeway, and support columns is another recent development. New pillars are being developed. Columns of concrete are embedded with strong rods of steel. These rods are wrapped with lateral bands of steel. When the huge weight of the freeway pushes down on the rods and pushes them outward, the steel bands resist the movement. This gives it sufficient strength to support the bridge superstructure. In an earthquake, this design is highly effective, as the steel rods embedded add a lot of strength and flexibility to the pillar.
43Top: Bridge Components Add size and weight to bridge’s footingAnchor with metal rods (pilings)Jacket of steel around columnThick cables help hold togetherTraditional concrete supports often lack the rigidity and strength to survive a major seismic disturbance. One thing that can be done to improve the seismic stability of these pillars is to reinforce the footings. Weight is added to them, and they are anchored with pilings, long metal rods that act as anchors. Steel casing is also added to the column to add even more support. The space between the column and the steel casing is filled with concrete. Strong metal cables are also used to secure the bridge deck and superstructure to the column. This design is highly effective in an earthquake. Top: Bridge ComponentsLeft: Cable System